Skin-Deep Immunity | The Scientist | Virology and Bioinformatics from |
The smallpox vaccine was the first, and arguably most successful, vaccine ever put into practice, and it was scratched into the skin of individuals. With the invention of syringes and hypodermic needles, vaccination shifted toward administration directly into the muscle, under the assumption that it is better to get a vaccine straight into the body. But it turns out scientists may have had it right the first time.

Via Ed Rybicki